Houston, Texas (KHOU) -- A mother out with her two children to go shopping became the victim of would-be purse snatchers, but a Good Samaritan armed with a gun came to the rescue.

"It happened so fast," said Brenda Vasquez, who manages the Family Dollar store in the 3400 block of Orlando Avenue in northeast Houston.

She witnessed the assault.

"This lady opens her car door, grabs the woman's purse and they reverse. While they're trying to reverse, the lady is holding on to her purse still, chasing them all the way to the middle."

That's when a perfect stranger intervened. He happened to be in his car in the parking lot when it happened.

"And that Good Samaritan came out, drew his weapon and scared them. And that's when he pulled them out of the car."

Someone snapped a picture of the man holding the two suspects at bay. A few minutes later, police arrived and took the male and female suspects into custody.

The man who first confronted them purchased some candy for his kids and drove away.

"The guy is something else," said Vasquez. "He's a hero."

Police were not releasing the names of either the Good Samaritan or the victim.

No one was injured.

PHOTOS: SunPass toll cheats!

Now here's a rocket scientist. Can you believe he rode in the trunk to keep the driver from paying a toll? You have to wonder if someone spotted him, because it's also illegal to ride in the trunk. (Photo: Florida DOT and WFOR CBS 4)

Even though he's standing up, you wouldn't call this toll cheat an upstanding citizen. He got the job done, and blocked the toll, but this is an easy way to get a trip to the hospital. (Photo: Florida DOT and WFOR CBS 4)

This cheat passed through the Bird Road toll on his motorcycle. He used lights to 'dazzle' the Sunpass camera. It was the brightest thing on his bike, driver included. (Photo: Florida DOT and WFOR CBS 4)

This is simple, but it worked. Just reach down and cover the tag. What he doesn't know is that eventually most of the people who do this get repeatedly caught, mostly by troopers staking out toll plazas looking for them. (Photo: Florida DOT and WFOR CBS 4)

Not really subtle, but apparently effective. Again, an easy target for a passing cop, because it's against the law to cover your tag. The fine will be far more than the toll would have been. This driver beat a toll at Cypress Creek. (Photo: Florida DOT and WFOR CBS 4)

This cheat slapped an envelope on his tag at the Homestead toll in South Dade. You have wonder how long he thought he could drive around with it before a cop would notice. (Photo: Florida DOT and WFOR CBS 4)